var BASE64_MAPPING = [
    'A',
    'B',
    'C',
    'D',
    'E',
    'F',
    'G',
    'H',
    'I',
    'J',
    'K',
    'L',
    'M',
    'N',
    'O',
    'P',
    'Q',
    'R',
    'S',
    'T',
    'U',
    'V',
    'W',
    'X',
    'Y',
    'Z',
    'a',
    'b',
    'c',
    'd',
    'e',
    'f',
    'g',
    'h',
    'i',
    'j',
    'k',
    'l',
    'm',
    'n',
    'o',
    'p',
    'q',
    'r',
    's',
    't',
    'u',
    'v',
    'w',
    'x',
    'y',
    'z',
    '0',
    '1',
    '2',
    '3',
    '4',
    '5',
    '6',
    '7',
    '8',
    '9',
    '+',
    '/'
];
/**
 *ascii convert to binary
 */

var _toBinary = function (ascii) {
    var binary = new Array();

    while (ascii > 0) {
        var b = ascii % 2;
        ascii = Math.floor(ascii / 2);
        binary.push(b);
    }
    /*
var len = binary.length;
if(6-len > 0){
    for(var i = 6-len ; i > 0 ; --i){
        binary.push(0);
    }
}*/

    binary.reverse();
    return binary;
};
/**
 *binary convert to decimal
 */

var _toDecimal = function (binary) {
    var dec = 0;
    var p = 0;

    for (var i = binary.length - 1; i >= 0; --i) {
        var b = binary[i];

        if (b == 1) {
            dec += Math.pow(2, p);
        }

        ++p;
    }

    return dec;
};
/**
 *unicode convert to utf-8
 */

var _toUTF8Binary = function (c, binaryArray) {
    var mustLen = 8 - (c + 1) + (c - 1) * 6;
    var fatLen = binaryArray.length;
    var diff = mustLen - fatLen;

    while (--diff >= 0) {
        binaryArray.unshift(0);
    }

    var binary = [];
    var _c = c;

    while (--_c >= 0) {
        binary.push(1);
    }

    binary.push(0);
    var i = 0,
        len = 8 - (c + 1);

    for (; i < len; ++i) {
        binary.push(binaryArray[i]);
    }

    for (var j = 0; j < c - 1; ++j) {
        binary.push(1);
        binary.push(0);
        var sum = 6;

        while (--sum >= 0) {
            binary.push(binaryArray[i++]);
        }
    }

    return binary;
};

var __BASE64 = {
    /**
     *BASE64 Encode
     */
    encoder: function (str) {
        var base64_Index = [];
        var binaryArray = [];

        for (var i = 0, len = str.length; i < len; ++i) {
            var unicode = str.charCodeAt(i);

            var _tmpBinary = _toBinary(unicode);

            if (unicode < 0x80) {
                var _tmpdiff = 8 - _tmpBinary.length;

                while (--_tmpdiff >= 0) {
                    _tmpBinary.unshift(0);
                }

                binaryArray = binaryArray.concat(_tmpBinary);
            } else if (unicode >= 0x80 && unicode <= 0x7ff) {
                binaryArray = binaryArray.concat(_toUTF8Binary(2, _tmpBinary));
            } else if (unicode >= 0x800 && unicode <= 0xffff) {
                //UTF-8 3byte
                binaryArray = binaryArray.concat(_toUTF8Binary(3, _tmpBinary));
            } else if (unicode >= 0x10000 && unicode <= 0x1fffff) {
                //UTF-8 4byte
                binaryArray = binaryArray.concat(_toUTF8Binary(4, _tmpBinary));
            } else if (unicode >= 0x200000 && unicode <= 0x3ffffff) {
                //UTF-8 5byte
                binaryArray = binaryArray.concat(_toUTF8Binary(5, _tmpBinary));
            } else if (unicode >= 4000000 && unicode <= 0x7fffffff) {
                //UTF-8 6byte
                binaryArray = binaryArray.concat(_toUTF8Binary(6, _tmpBinary));
            }
        }

        var extra_Zero_Count = 0;

        for (var i = 0, len = binaryArray.length; i < len; i += 6) {
            var diff = i + 6 - len;

            if (diff == 2) {
                extra_Zero_Count = 2;
            } else if (diff == 4) {
                extra_Zero_Count = 4;
            } //if(extra_Zero_Count > 0){
            //	len += extra_Zero_Count+1;
            //}

            var _tmpExtra_Zero_Count = extra_Zero_Count;

            while (--_tmpExtra_Zero_Count >= 0) {
                binaryArray.push(0);
            }

            base64_Index.push(_toDecimal(binaryArray.slice(i, i + 6)));
        }

        var base64 = '';

        for (var i = 0, len = base64_Index.length; i < len; ++i) {
            base64 += BASE64_MAPPING[base64_Index[i]];
        }

        for (var i = 0, len = extra_Zero_Count / 2; i < len; ++i) {
            base64 += '=';
        }

        return base64;
    },

    /**
     *BASE64  Decode for UTF-8
     */
    decoder: function (_base64Str) {
        var _len = _base64Str.length;
        var extra_Zero_Count = 0;
        /**
         *计算在进行BASE64编码的时候，补了几个0
         */

        if (_base64Str.charAt(_len - 1) == '=') {
            //alert(_base64Str.charAt(_len-1));
            //alert(_base64Str.charAt(_len-2));
            if (_base64Str.charAt(_len - 2) == '=') {
                //两个等号说明补了4个0
                extra_Zero_Count = 4;
                _base64Str = _base64Str.substring(0, _len - 2);
            } else {
                //一个等号说明补了2个0
                extra_Zero_Count = 2;
                _base64Str = _base64Str.substring(0, _len - 1);
            }
        }

        var binaryArray = [];

        for (var i = 0, len = _base64Str.length; i < len; ++i) {
            var c = _base64Str.charAt(i);

            for (var j = 0, size = BASE64_MAPPING.length; j < size; ++j) {
                if (c == BASE64_MAPPING[j]) {
                    var _tmp = _toBinary(j);
                    /*不足6位的补0*/

                    var _tmpLen = _tmp.length;

                    if (6 - _tmpLen > 0) {
                        for (var k = 6 - _tmpLen; k > 0; --k) {
                            _tmp.unshift(0);
                        }
                    }

                    binaryArray = binaryArray.concat(_tmp);
                    break;
                }
            }
        }

        if (extra_Zero_Count > 0) {
            binaryArray = binaryArray.slice(0, binaryArray.length - extra_Zero_Count);
        }

        var unicode = [];
        var unicodeBinary = [];

        for (var i = 0, len = binaryArray.length; i < len; ) {
            if (binaryArray[i] == 0) {
                unicode = unicode.concat(_toDecimal(binaryArray.slice(i, i + 8)));
                i += 8;
            } else {
                var sum = 0;

                while (i < len) {
                    if (binaryArray[i] == 1) {
                        ++sum;
                    } else {
                        break;
                    }

                    ++i;
                }

                unicodeBinary = unicodeBinary.concat(binaryArray.slice(i + 1, i + 8 - sum));
                i += 8 - sum;

                while (sum > 1) {
                    unicodeBinary = unicodeBinary.concat(binaryArray.slice(i + 2, i + 8));
                    i += 8;
                    --sum;
                }

                unicode = unicode.concat(_toDecimal(unicodeBinary));
                unicodeBinary = [];
            }
        }

        return unicode;
    }
}; //window.BASE64 = __BASE64;

export default __BASE64;
